The present invention relates to devices, such as X,Y plotters, for drawing lines on a receiving surface, as provided for example by a sheet of paper, and deals more particularly with a pen and ink supply unit for use with such a device which unit is expendable, is easily attached to and removed from the drawing device to allow the quick replacement of one unit by another one, and which unit contains a large supply of ink to give it a long service life.
Plotters and other line drawing devices using pens, such as ball point pens or capillary tube pens, for applying ink to receiving surfaces have the requirement that the pen be given an adequate supply of ink during a line drawing process to assure the production of high quality gap free lines. For operation of the devices at high drawing speeds, this usually demands that the ink supplied to the pen be pressureized.
Various attempts have been made in the past to deal with the supplying of ink under pressure to a pen of the aforegoing character. One presently used method is to supply each pen in a form including a pen tube containing a quantity of ink and combined with a small capsule of pressurized air or other gas which pressurizes the ink in the tube during the life of the pen. A disadvantage of this, however, is that each pen tube contains only a relatively small amount of ink, giving the pen a relatively short life and therefore requiring frequent stoppage of the line drawing device for pen replacement. Further, unless watched carefully, devices using such pens often continue to operate long after the pen runs out of ink, therefore requiring a troublesome restart and redoing of some work after the empty pen has been replaced by a new one.
Another known method of supplying pressurized ink to a pen is to provide a separate refillable ink reservoir capable of holding a large quantity of ink and to which a quantity of pressurized air or other gas overlying the ink in the reservoir is applied. Disadvantages of this method are that the refilling of the reservoir requires the direct handling of ink which, unless done very carefully, can lead to spillage and very messy conditions. Also, it is difficult in this method to change to a different type or color of ink and to change pens as may be desired to draw with different types or colors of inks or to create lines of different width.
The general object of this invention is therefore to provide a pen and ink supply unit for use with a plotter or similar line drawing device which overcomes the aforementioned problems of known ink supply methods and which has other advantageous features. More particularly, the pen and ink supply unit of the present invention is one wherein a pen and ink reservoir are combined as a unit assembly which is readily attachable to and removeable from the line drawing device to permit quick replacement of an out of ink unit with a new unit or to permit quick exchange of units to change the color or type of ink or the width of line drawn. The unit further contains a large quantity of ink allowing the line drawing device after receiving a new unit to run for a very long item before the ink becomes depleted and the unit in need of replacement.
Further, the pen and ink supply units of the invention are prefilled with ink, are nonrefillable, and are of such low cost that they may be thrown away when empty, avoiding the need for the device operator to directly handle ink and thereby avoiding the likelihood of ink spillage.
A further object of the invention is to provide a pen and ink supply unit of the aforegoing character whereby to eliminate or minimize the possibility of ink leakage, the units may be shipped and stored in non-pressurized condition, with the ink in the supply reservoir of each unit not being pressurized until immediately before or after the unit is attached to the pen head of a plotter.
Other objects and advantages of the invention will be apparent from the following description of detailed embodiments of the invention and from the accompanying drawings and claims.